USB devices are widely used because it is portable and supports plug-and-play. Currently, USB devices mainly includes two working modes: For some USB devices, such as a USB CDROM and a USB mouse, their drivers are already integrated in the operating system, so they may realize plug-and-play; for other USB devices, such as USB network adapters, their drivers should be installed before these USB devices may be used.
Assume that a USB device has both the preceding working modes, for example, the USB device has two working modes, namely, a USB CDROM mode and a USB network adapter mode, and that the default working mode of the USB device is the USB CDROM mode. To enable a user to use the USB network adapter mode, the USB device should judge the capability of a computer (PC for short) which is connected to the USB device to decide whether the USB device may work in the USB network adapter mode. In the prior art, an auxiliary program or an additional driver is used to enable the USB device to know whether the USB device may work in the USB network adapter mode. Specifically, for a solution in which an auxiliary program is used in the prior art, when a user runs a USB network adapter driver provided by an equipment maker on a PC, an auxiliary program should be run on the PC at the same time. At run time, the auxiliary program shakes hands with the USB device to inform the USB device that the USB network adapter driver has been installed on the PC so that the USB device may work in the USB network adapter mode. If there is no handshake information, the USB device works in the USB CDROM mode. For a solution where an additional driver s is used in the prior art, when a user runs a USB network adapter driver provided by an equipment maker on a PC, an additional driver, such as different kinds of filter drivers, should be run on the PC at the same time. When a USB device is being used, the PC first attempts to load the filter driver. The filter driver may shake hands with the USB device to inform the USB device that the USB network adapter driver have been installed on the PC so that the USB device may work in the USB network adapter mode.
For the preceding solutions in the prior art, a special auxiliary program or an additional driver should be developed, so the solutions are complicate; in addition, a risk of incompatibility may exist.